1. Field of the Invention
The present invention relates to a toner cartridge applied to an electrostatic process image forming apparatus such as an electrophotographic copying machine for supplying toner for visualizing an electrostatic image.
2. Description of the Prior Art
In an electrostatic process image forming apparatus such as an electrostatic process copying machine and a laser beam printer, an image is formed in the following manner. More specifically, the surface of a photoreceptor uniformly charged is exposed corresponding to an image to be formed. Consequently, an electrostatic latent image corresponding to an image to be recorded is formed on the surface of the photoreceptor. The electrostatic latent image is developed into a toner image by a developing device. The toner image is transferred to paper, and the toner image transferred is further fixed on the paper, to complete printing.
Toner is supplied to the developing device from a toner hopper inside of the image forming apparatus. The toner in the toner hopper is consumed as the image is formed. Consequently, when there is no toner left in the toner hopper, toner must be supplied. It is a toner cartridge that is used so as to supply the toner.
Examples of the toner cartridge conventionally used include a toner cartridge in which an opening of a cartridge body which is a container for containing a constant amount of toner is sealed by affixing a film-shaped sealing member. At the time of supplying toner, the toner cartridge is mounted on the toner hopper, so that the sealing member is stripped. Consequently, the toner in the cartridge body is supplied to the toner hopper through the opening.
Such a toner cartridge is disclosed in, for example, Japanese Utility Model Laid-Open Gazette No. 28447/1979. In the prior art disclosed in the gazette, a sealing member is folded in one end of an opening of a cartridge body, and is extended to the other end of the opening. After the toner cartridge is mounted on a toner hopper, a worker pulls out a front end of the sealing member folded. Consequently, the sealing member is stripped from the one end of the above described opening to the other end thereof.
In the prior art, however, a surface to which toner adheres of the sealing member is exposed, resulting in contamination by toner. More specifically, the toner adhering to the surface of the sealing member is scattered, to make clothes of the worker and peripheral devices dirty. Further, in the prior art, the front end of the sealing member must be pulled out over a length which is twice the length of the opening so as to completely open the opening of the cartridge body. That is, the stroke for stripping is long. In addition, a sealing member having a length which is twice the length of the opening is required, so that a large part of the sealing member is ineffective.
Japanese Utility Model Laid-Open Gazette No. 41364/1984 discloses the prior art in which the problem of contamination by toner is overcome. More specifically, in the prior art, a sealing member is covered with a slide cover slid along an opening of a cartridge body. The slide cover is first pulled out and then, the sealing member is pulled out. At this time, a toner adhering surface of the sealing member is opposed to the slide cover. Consequently, the toner adhering surface of the sealing member is shielded by the slide cover, thereby to make it possible to prevent the contamination by toner. In the prior art, however, a state where the sealing member is disposed is the same as that in Japanese Utility Model Laid-Open Gazette No. 28447/1979, so that the problem that the stroke for stripping is long and the problem that a large part of the sealing member is ineffective are not improved.
The other prior art in which the problem of contamination by toner is overcome is disclosed in Japanese Utility Model Laid-Open Gazette No. 132962/1988. The toner cartridge disclosed in this gazette is provided with a shutter for opening or closing an opening of a cartridge body. An extended part connecting with a part where the opening is sealed of the sealing member is led to a lower surface of the shutter, and is further led to a portion between the opening and the shutter through a first slit formed in a front end of the shutter. The extended part of the sealing member between the opening and the shutter is further led to the lower surface of the shutter through a second slit formed in a rear end of the shutter and then, is led to an upper surface of the shutter again through a third slit formed on the rear end side of the second slit. A front end of the extended part of the sealing member adheres to a peripheral edge part of the opening of the toner cartridge.
When the shutter is pulled out of the cartridge body, the sealing member is towed by the third slit while being moved through the first, second and third slits. Consequently, the sealing member is stripped from the opening. At this time, a toner adhering surface is opposed to the upper surface of the shutter, so that there occurs no problem of contamination by toner.
Also in this prior art, however, the problem that the stroke for stripping is long and the problem that a large part of the sealing member is ineffective are not solved.
On the other hand, Japanese Utility Model Laid-Open Gazette No. 41365/1984 discloses the still other prior art. In a toner cartridge disclosed in this gazette, a state where a sealing member is disposed is the same as that in the toner cartridge disclosed in Japanese Utility Model Laid-Open Gazette No. 28147/1979. In addition, a slide cover is provided in the same manner as that in the toner cartridge disclosed in Japanese Utility Model Laid-Open Gazette No. 41364/1984. The toner cartridge differs from the toner cartridge disclosed in Japanese Utility Model Laid-Open Gazette No. 41364/1984 in that a front end of a sealing member folded adheres to an upper surface of the slide cover. If the slide cover is completely pulled out, the sealing member is stripped to the middle of the opening. At this time, the sealing member is exposed to the upper surface of the slide cover. Accordingly, a worker takes the exposed part of the sealing member in his hand to pull the same, thereby to make it possible to completely strip the sealing member from the opening.
In the prior art, the stroke length required to strip the sealing member is reduced to approximately 1.5 times the length of the opening. However, a worker must directly take a part to which toner adheres of the sealing member, so that the hand and clothes are liable to be dirty. Accordingly, the problem of contamination by toner cannot be avoided. In addition, the problem that a large part of the sealing member is ineffective is not solved.
The prior art for reducing the stroke length is also disclosed in Japanese Patent Publication No. 60142/1989 and Japanese Patent Laid-Open Gazette No. 280781/1989. In a toner cartridge disclosed in Japanese Patent Publication No. 60142/1989, a sealing member is formed in a loop shape. In addition, there is provided a slidable shutter for opening or closing an opening of a cartridge body, and the shutter is disposed so as to be enclosed by the sealing member. If the shutter is slid, a loop of the sealing member follows the shutter, so that the sealing member is stripped in a direction to slide the shutter. Consequently, the shutter is slid by a length equal to the length of the opening, thereby to make it possible to completely strip the sealing member. In the above described manner, the stroke length becomes approximately equal to the length of the opening.
In the prior art disclosed in Japanese Patent Laid-Open Gazette No. 280781/1989, a shutter is provided slidably with respect to an opening of a cartridge body. In addition, a sealing member is disposed with it being folded in the same manner as that in the toner cartridge disclosed in Japanese Utility Model Laid-Open Gazette No. 28447/1979, and a front end of the sealing member adheres to the cartridge body through a hole formed in the shutter. The operation in the prior art is approximately the same as the operation disclosed in Japanese Patent Publication No. 60142/1989.
In the prior art disclosed in Japanese Patent Publication No. 60142/1989 and the prior art disclosed in Japanese Patent Laid-Open Gazette No. 280781/1989, a toner adhering surface of the sealing member is exposed to the lower surface as the shutter is slid. Consequently, toner is liable to be dropped, so that the problem of contamination by toner is unavoidable. Moreover, the sealing member must have a length which is twice the length of the opening.
The above described Japanese Patent Publication No. 60142/1989 also discloses a toner cartridge so adapted that a pulley is provided in each of a front end and a rear end of the shutter, the loop-shaped sealing member is wound around the pulley, and the loop of the sealing member is formed between the shutter and the opening of a cartridge body. In this toner cartridge, the toner adhering surface of the sealing member enters a portion between the opening of the cartridge body and the shutter, so that the problem of contamination by toner is restrained. However, the problem that a large part of the sealing member is ineffective cannot be avoided even by the prior art.